Most ovens with a radiant heat source have a load dependency that yields different cooking results depending on how many food items are cooked simultaneously and the frequency of loading the food items. A typical example is a conveyer toaster for commercial food service where the browning of the toast will vary due to the load factor (continuous use or single piece processing) as well as the age or use of the toaster itself. Manufacturers have attempted to deal with some of these issues, but the major disadvantages are that the toasters do not react quickly and accurately and do not deal with the variation in radiation that typically occurs over the lifetime of the appliance. The most common approach takes information from an oven temperature sensor and adjusts the conveyor speed as described, e.g., in U.S. Pat. No. 5,821,503 and U.S. Pat. No. 6,624,396. This approach has the disadvantage of having a long processing time when the load factor increases.
One of the weakest parts of appliances having a conveyor is the gearbox that is normally required on the motor driving the conveyor. Due to the low rotational speeds required by the conveyor, it is difficult to find a motor with sufficient torque without a gearbox. If the motor has a gearbox, it is normally expensive due to the requirements of durability and side-loading of the drive shaft.
Thus, there is a need for consistent cooking of food items that is independent of load factors and age of the toasting appliance.
There is a need for minimization of cooking variations due to main voltage fluctuations.
There is a need for consistent cooking of food items for the same cooking set point.
There is a need for minimization of the variation in processing time for different load factors.
There is a need for a conveyor drive without a gear box.
There is need for an improved temperature control.